JPS63144440A - Production of optical disk - Google Patents

Abstract

PURPOSE:To attain a simple production method of an optical disk with no mixture of air bubbles by adhering two opposite substrates together under vacuum via an adhesive and curing the adhesive in the air in the adhering process of the optical disk. CONSTITUTION:The adhesive 4 is applied onto a substrate 1 containing a recording medium 3 and another substrate 1 also containing a medium 3 is set opposite to the other substrate 1 with a secured distance. These two substrates 1 are put into a vacuum container 5 and a vacuum open/close valve 6 is opened to exhaust the air in the container 5. In this case, the adhesive 4 applied on the surface of the substrate 1 is also degassed. Then both substrates 1 are put on each other and the minute air bubbles are mixed into the layer of the adhesive 4. Then the valve 6 is operated to supply again the air into the container 5. As a result, the 1atm. pressure is applied to an optical disk and therefore the minute air bubbles remaining in the adhesive 4 are compressed to be minimized. The sizes of these bubbles are further reduced when the degree of vacuum is increased. Then the adhesive 4 of the optical disk put back into the air is cured as it is. Thus two optical disks are adhered together.

Description

[Detailed description of the invention] Industrial applications The present invention relates to recording used as a high-density recording medium.

The present invention relates to a method of manufacturing a reproducible or erasable optical disc.

Conventional optical disks have a structure in which some are made up of a single disk, while others are made up of two disks pasted together. The optical disc related to the present invention is constructed by bonding two discs together, and a description of the optical disc comprised of one disc will be omitted.

Hereinafter, the structure of the above-mentioned optical disc and its conventional manufacturing method will be explained with reference to the drawings.

FIG. 2 is a structural diagram of an optical disc. 1 is a substrate, 2 is a guide groove, 3 is a recording medium, and 4 is an adhesive.

Note that although the drawing shows a double-sided type, a bonded type used on one side is also the same.

Generally, the structure of the substrate 1 is such that the guide grooves 2 are formed directly on the resin, or the guide grooves 2 are formed on the glass surface using the resin. Guide groove 2 on the first surface of the board
A thin film recording medium 3 is formed on the side.

The two substrates 1 on which the recording medium 3 is formed are connected to the recording medium 3.
They are bonded together with an adhesive 4 so that they face each other.

Problems to be Solved by the Invention However, the conventional manufacturing method described above had the following problems.

That is, when bonding, air bubbles are likely to be generated in the adhesive layer 4 due to air bubbles contained in the adhesive 4 or due to air intake when the substrates 1 are stacked. Due to the difference in thermal expansion coefficient between the bubbles and the adhesive 4, the pressure applied to the substrate 1 becomes uneven, and traces of the bubbles are transferred to the substrate 1. This increases optical disc errors. At this time, the layer of the recording medium 3 is much thinner than the layer of the adhesive 4, and the pressure is directly transmitted to the substrate 1 side without suppressing the non-uniformity of pressure due to air bubbles. For this reason, the conventional method of bonding optical discs requires a very complicated method to prevent air bubbles from being introduced, and has the drawback of poor yield.

In view of the above-mentioned drawbacks, the present invention provides a method for manufacturing an optical disk that is simple in bonding and does not contain air bubbles.

Means to Solve the Problems In order to achieve the above object, the present invention is to bond opposing substrates together in a vacuum via an adhesive in the process of bonding optical discs, and to harden the adhesive in the atmosphere. .

Function: Since the present invention uses the above-described manufacturing method to bond in vacuum, the adhesive is degassed and the substrate surface is degassed. Furthermore, since the atmosphere is a vacuum, the inclusion of air bubbles is minimal. When this optical disk is returned to the atmosphere, it is pressed at 1 atm, and the tiny remaining bubbles become even smaller in the atmosphere, reaching a size that cannot be detected as an error.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to the drawings.

Figure 1B shows the manufacturing process for bonding optical discs according to the present invention.

In FIG. 1, 1 is a substrate, 2 is a guide groove, 3 is a recording medium, 4 is an adhesive, 6 is a vacuum container, and 6 is a vacuum-sealable pulp.

Figure 2 shows the state of the person before pasting.

First, the adhesive 4 is applied onto the substrate 1 on which the recording medium 3 is formed, and the substrate 1 on which the recording medium 3 is also formed is placed so as to face each other at a distance. This entire configuration is assembled into a vacuum container 5.
When the vacuum opening/closing valve 6 is opened, the air inside the vacuum container S is removed. At this time, the surface of the substrate 1 and the adhesive 3 are degassed at the same time.

FIG. 1B shows the drawings pasted together inside the vacuum container 6.

The two substrates 1 described above are stacked one on top of the other with a distance between them. At this time, there are very few air bubbles in the layer of adhesive 4. Next, the vacuum opening/closing pulp 6 is operated to return the inside of the vacuum container 6 to the atmosphere.

As a result, a pressure of 1 atmosphere is applied to the optical disc, and minute air bubbles remaining in the adhesive 4 are compressed and further reduced in size. Its size is 1/76000, assuming that the degree of vacuum is 10 Torr. Furthermore, if the degree of vacuum is increased beyond this level, the size of the bubbles will naturally become smaller.

By directly curing the adhesive 4 on the optical disks returned to the atmosphere, the bonding of the optical disks is completed.

By adopting the manufacturing method of the present invention as described above,
Both the size and number of bubbles in the adhesive layer of the optical disc are significantly reduced to the extent that they are not detected as errors. Furthermore, since a vacuum is used, the equipment is simple and the yield is greatly improved.

[Brief explanation of the drawing]

FIG. 1 is a process diagram of an optical disc bonding process showing a method of manufacturing an optical disc in an embodiment of the present invention, and FIG. 2 is a structural diagram of the optical disc. 1... Board, 2... Guide groove, 3...
...Recording medium, 4...Adhesive, 5...
Vacuum container, 6... Vacuum opening/closing pulp.

Claims (1)

[Claims] A method for manufacturing an optical disk, which comprises, in the step of bonding optical disks, bonding substrates facing each other with an adhesive in a vacuum, and curing the adhesive in the atmosphere.